I guess I'm just used to using automation on whatever track content is there - midi piano roll, or audio. Just the way that most sequencers work these days. Very quick to mix fades and section volume changes on individual tracks whether or not they are midi or audio. If I was an RB customer, I'd put this on the wishlist right away. In my DAW, Volume and pan fades via automation seem to use no appreciable difference in resource usage on either midi or audio tracks - I believe because of where the developer chose to place the automation in the audio stream.

I guess I just assumed that was the de rigeur standard way of doing automation.